Maisha,
The trouble with "modest" consumption of alcohol is that every JW has their own idea of what constitutes "modest consumption."
Early on, I was warned off the JWs a non-JW relative, following her attendance at a Jehovahs Witness wedding reception. She was quite appalled by the heavy drinking that she saw going on at that event.
Later, I knew an elder who was rather concerned when named to attend the next session of the Kingdom Ministry School. He told us that he was going to "have to dry himself out beforehand" - referring to his fondness for apple wine, which he consumed for by the flagon full. For nine months after the 1975 debacle, that same elder never ventured out once in field service, and would regularly demolish a 2 litre flagon of sherry over the course of one night. Throughout all this, he kept his position, and was always quite highly regarded in the JW community. (a lot to do with his being a "closet" drinker, I think - you would never ever see him in any public bar around the place).
I myself was not exactly squeaky clean when it came to the subject of the brown bottle. Raised by parents who were modest drinkers, I was first introduced to drinking when I began associating with the local congregation. There was considerable social pressure to indulge in the stuff, and as others have noted, it was an easy habit to adopt - being one of the few escapes / indulgences / releases (call it what you will!) that a Witness is permitted to have.
The "guidance" that I received from the brother whom I studied with was that it was all-right to have the "occassional" heavy session on the grog, but one should still at all times "have all their faculties" about them. (This is indeed what he - an elder and regular pioneer - did).
The immediate problem here is in precisely defining what constitutes "occassional", and where the boundary line between "still having all ones faculties" and having lost them is located!
In my 28 years "in the Truth", I both witnessed - and participated in - much abuse of alcohol.
Bill.